Manas occupies a position in the twenty-five tattvas that a modern reader is likely to find counter-intuitive: it is grouped with the sense organs and the active organs, one of the "eleven organs" produced by ahamkara's sattvic aspect, rather than with buddhi as a seat of awareness. The classical system reserves consciousness entirely for purusha and reserves the specific work of discernment for buddhi; manas, by comparison, is assigned a narrower and more mechanical job, gathering the separate outputs of the five perceptual organs, hearing, touch, sight, taste and smell, and synthesising them into one coherent presented object.
Without manas, Samkhya's texts suggest, the five senses would deliver disconnected impressions with nothing unifying them into a single experience of, say, one particular mango rather than five unrelated data streams of colour, texture, aroma and so on. Manas performs that unification, and it performs the complementary function on the output side, directing the five organs of action, speech, grasping, locomotion, excretion and generation, once buddhi has rendered its determination and ahamkara has claimed the resulting intention as its own.
Because manas belongs entirely to prakriti and carries no consciousness of its own, its coordinating activity is, on this account, no more mysterious than any other mechanical process the unconscious material world performs; the appearance of a unified, aware subject doing the coordinating is supplied only by proximity to purusha, exactly as with every other tattva downstream of prakriti's original disturbance.